Tube drier



C. A. SIMPSON TUBE DRIER 2 Sheets-Sheet 1 Filed Feb. 27. 1947 CHARLESA.S|MP5ON 02 MM ATTORNEY C. A. SIMPSON Oct. 24, 1950 TUBE DRIER 2Sheets$heet 2 Filed Feb. 27, 1947 INVENTOR CHARLES A. SIMPSON Inf 2?ZUZ/ZQM ATTORNEY Patented Oct. 24, 1950 TUBE DRIER Charles A. Simpson,Norwalk, Conn., assignor to Voltarc Tubes, Inc., Norwalk, Conn.,'acorporation of New Jersey Application February 27, 1947, Serial No.731,239

1 Glaim. 1

This invention relates to apparatus for drying the interior surface ofelongated tubes. More particularly it relates to a machine forcontinuouslyrotating and conveying such tubes while they are undergoinga controlled sequence of drying rates.

While not limited thereto, this invention is especially applicable tothe manufacture of fluorescent coated glass tubing of the types nowwidely used for fluorescent lamps and fluorescent tube signs.

In the particular manufacture just mentioned, the fluorescent powder isusually applied to the interior of the tube by means of a liquid vehicleor lacquer, the mixed powder and liquid being called a suspension. Thesuspension is run into the tube so that it coats substantially theentire tube. It is then necessary to drain from the interior of the tubethe excess suspension over that needed to supply the desired amount ofphosphor, to spread evenly over the tube wall the remaining suspension,and finally to evaporate substantially all the liquid from the remainingsuspension so that the phosphor will be left deposited in a layer ofsolid material having the desired thickness.

The present invention comprises an automatic machine into which are fedtubes of the character just described. The tubes may be fed inimmediately preceding coating, or immediately after coating and prior tothe completion of draining. The machine imparts to the tube a rotarymotion which promotes the uniform distribution of the desired liquidfilm. Simultaneously a current of any desired gas, such as air,

is blown downwardly through the tube, in order to hasten evaporation ofthe vehicle from the film. Additionally, means are provided for recoveryof the excess liquid thus removed from the tube, and also for theremoval of the gas which has passed through the tube and is now ladenwith the vehicle in the form of vapor, it being possible to recover theliquid, if desired, from such gas by processes well known in the art.

An object of this invention is to provide a tube drying machine in whichthe tubes are continuously conveyed from the inlet to the outlet of themachine by an endless belt, along which the tubes may be spaced ateither regular or irregular intervals, yet each tube will undergo asubstantially identical draining and drying cycle.

An additional object is to provide a tube drying machine of thecharacter just described, in which the transitional movement imparted tothe tubes by the endless belt automatically brings about an additionalmovement of axial rotation of each tube, without the necessity ofemploying any discrete devices for securing such axial rotation.

Another purpose of this invention is to provide a-tube dryin machine inwhich the tubes, during transit therethrough, are positively butyieldingly positioned at any given instant between retaining membershaving a high degree of resiliency, whereby fracture and breakage oftubes formed of glass or other easily frangible material aresubstantially obviated.

Yet another object of this invention is to provide a tube drying machinewhich may easily and rapidly be adjusted for use with tubes of varyingdiameter.

Additional purposes and advantages of this invention will be apparent tothose skilled in the art from the following specification, and. fromreference to the hereunto annexed drawings, in which:

Fig. 1 is a side elevationalviewof one embodiment of this invention,

Fig. 2 is anend elevational view of the device of Fig 1,

Fig. 3 is a top plan view of the device of Fig. 1, with certain elementspartly broken away to show tubes passin through the device, and

Fig. 4 is a sectional view on the lines 44 of Fig. 1.

Referring'now to the drawings, a supporting framework Ill carries at oneend thereof a pulley ll mounted near the upper end of a drive shaft l2,and a substantially identical pulley l3 mounted near the lower end ofthe same shaft. The shaft is supported by, and rotates within bearingsl4 and I5, these latter being mounted by brackets 16 and I! upon theframework. Drive shaft l2 carries a gear I8, which is driven by a wormIS. The worm is in turn driven by any suitable source of mechanicalenergy, such as the motor shown at 20. the device are mounted pulleys 2iand 22, by suitable brackets 23 and 24, Each of these last mentionedpulleys constitutes an idler. A belt 25, formed of any suitable materialhaving suificient resiliency, such as rubber, connects pulleys l l and 2I, while a similar belt 26 connects pulleys l3 and 22.. Due to the factthat pulleys II and I3 are driven at identical speed, belts 25 and 26'will move longitudinally at substantially identical rate of speed.

Parallel to belt 25 is positioned a supporting member 21, having one endthereof curved away At the opposite end of ing circulation through thetubes.

-chine, for purposes of recovery.

- 3 from pulley 22, so as to allow the ready insertion of a tube at thispoint. A correspondingly positioned member 28 lies parallel to belt 26.Supporting members 21 and 28 are each lined with respective strips 29upon the faces of the members adjacent to the belts. These linings areformed of an extremely resilient material, spongerubber having been'found suitable for the purpose. The supporting members 21 and 28 areheld in the desired positions by laterally extending cross pieces 30 and3|. The cross pieces are each provided with slots 32. Adjustin screws 33pass through these slots into the main framework 10. It is thereforepossible, by loosening these screws, to alter the distance between thesurface of the resilient lining 29 and the respective belts. so as toaccommodate tubes of different diameters.

Extending longitudinally along the framework in a position immediatelyabove the upper extrernities of the tubes is fixed an'air ccnduit' i i,provided with a series of apertures directed downwardly so that theopening at th upper end of each tube will pass directly beneath theseapertures. Conduit Ed is supplied with a suitable gaseous drying medium,such as air, under a pressure sufiicient to establish the desired dry- Ahand valve, not shown, is sufficient to regulate the air flow tocorrespond with various tube diameters, tube lengths, or vehicles ofdifferent volatility.

Along the lower portion of the framework is arranged a second conduit36. veniently be formed so as to have a lower, generally rectangularportion, the lateral walls of which may be bent inwardly, as shown at31, thus providing two lips, between which pass the tubes progressingthrough the machine. The liquid material draining out of the tubes flowsalong conduit 36, which is preferably slightly inclined, so that theliquid gathering therein will drain out of the conduit at one end of thema- Any suitable gas exhaust mechanism (not shown)- may be connected toconduit 36, so that the vapor-laden gases also entering the conduit willbe removed therefrom rather than escaping into the atmosphere, wherethey may constitute a fire or health hazard. A control (not shown) isused to regulate the amount of suction to control the rate of drying,and hence the coating distribution, in the manner described above forconduit 36. As

This may con- 4 previously mentioned, the vaporized solvent may berecovered from such exhaust gases by any suitable means, as well knownin the art.

While there have been shown and described certain embodiments of thisinvention it is to be understood that many variations thereof will beapparent to those skilled in the art and accordingly the scope of thisinvention is limited only by the hereunto appended claim.

What is claimed as new and desired to be secured by Letters Patent 0fthe United States is:

A device for drying the interior of vertically disposed tubing,including two horizontal belts having corresponding portions equidistantfrom one another, means for moving said belts at substantially identicalspeeds, two strips of resilient material respectively disposed atsubstantially equal distances from each of said belts and spacedtherefrom by a distance less than the outside diameter of said tubing,means for per mitting the insertion of said tubing near 'one end of saidstrips and between said strips' an'd said belts, whereby rotation andtransition ofisaid tubing is simultaneously and solely caused, by'themotion of said belts, a gas conduit disposedisubstantially parallel tosaid belts and immediately above said tubing and having thereindownwardly directed apertures, allowing a drying gas to be blowndownwardly through said moving tubing, and also including a conduitdisposed substantially parallel to said belts, immediately below saidtubing, whereby fluid material leaving said tubing at the bottom thereofenters said conduit, said conduit having a cross section broader at thebottom and narrowing at the top until the two vertical sides thereofapproach one another so closely as to embrace the lower end of saidtubing, whereby evaporation of said fluid material is reduced.

' CHARLESA. SIMPSON.

Number Name 2,159,318 Carter May 23, 1939 2,337,740 Albright Dec. 28,1943 2,415,198

Webb Feb. 4, 1947

